Re: [EnergyPlus_Support] Re: Plant Demand Error

["Michael J. Witte" <mjwitte@xxxxxxxx>]

> I have check the coil total cooling load. The sum of the two coils is less
> than 27kW.

Not exactly.  The sum of "Fan Coil Total Cooling Rate[W](Hourly)" is 
approximately 27kW.  But the sum of "Total Water Cooling Coil Rate[W](Hourly)" 
is approximately 35kW, and it exactly matches the plant loop cooling demand 
each hour.

What's the difference?  See the definition of "Fan Coil Total Cooling Rate" in 
the Input Output reference.  It is the cooling delivered to the zone.

"Total Water Cooling Coil Rate" is the coil load.  The difference is the 
outside air load.

Mike


On 20 Jul 2006 at 9:14, energypluser wrote:

> Dear Mike,
> 
> I have check the coil total cooling load. The sum of the two coils is less
> than 27kW.
> But the plant cooling demand is still 35kW.
> In the csv file, I find that the sum of the flow rate through the two coils is
> equal to that of the 
> chiller. And the temperature difference of the coil inlet & outlet node is
> almost the same of 
> the chiller.
> I use the formula Q=Cp*Mdot*DeltaT to calculate the heat transfered.
> I find that the heat transfered from the chiller is corresponding to the plant
> cooling demand.
> But the heat transfered in the two coils is corresponding to the zone cooling
> demand. And it 
> is 10kW bigger than the sum of the coil total cooling load from the csv
> file.
> I really do not think that the pump and fan can add 10kW cooling demand to the
> loop.
> Can I just increase the setpoint of the cooling loop to fix this problem?
> I remember that the coil cooling demand and the loop cooling demand is matched
> before I 
> added the domestic water object. Does it have some influence on the loop
> cooling demand?
> The domestic water is operating when the coil are suppling chilled air to the
> zones.
> Thank you in advance
> 
> mac.cz
> 
> 
> 
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the
> "search" button.
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 


========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx





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